This report introduces the methodology used by the wCorr R package for computing the Pearson, Spearman, polyserial, polyserial, polychoric and tetrachoric correlations, with and without weights applied. Simulation evidence is presented to show correctness of the methods, including an examination of the bias and consistency.
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24 Apr 2017
Achievement levels are important yardsticks in the National Assessment of Educational Progress (NAEP) program. In this document, we provide a detailed description of the plausible value method and demonstrate the method by replicating the analyses using SAS and comparing the replicated analysis results with those produced with NAEP Data Explorer. It is intended to provide a complete document for NAEP data users to easily adapt the methodologies with other statistical software packages such as SAS, Stata, R, and so on.
29 Jan 2016
Because NAEP is transitioning its paper-and-pencil assessments to a digital format, it is important to understand the relationship between students' familiarity with computers and their performance. This study, which analyzed three of NAEP's early digital-based assessments, found that home computer access was positively related to student performance.